THE STONE; If Peas Can Talk, Should We Eat Them?

By MICHAEL MARDER

Published: April 29, 2012

Imagine a being capable of processing, remembering and sharing information -- a being with potentialities proper to it and inhabiting a world of its own. Given this brief description, most of us will think of a human person, some will associate it with an animal, and virtually no one's imagination will conjure up a plant.

Since Nov. 2, however, one possible answer to the riddle is Pisumsativum, a species colloquially known as the common pea. On that day, a team of scientists from the Blaustein Institute for Desert Research at Ben-Gurion University in Israel published the results of its peer-reviewed research, revealing that a pea plant subjected to drought conditions communicated its stress to other such plants, with which it shared its soil. In other words, through the roots, it relayed to its neighbors the biochemical message about the onset of drought, prompting them to react as though they, too, were in a similar predicament.

Curiously, having received the signal, plants not directly affected by this particular environmental stress factor were better able to withstand adverse conditions when they actually occurred. This means that the recipients of biochemical communication could draw on their ''memories'' -- information stored at the cellular level -- to activate appropriate defenses and adaptive responses when the need arose.

In 1973, the publication of ''The Secret Life of Plants,'' by Peter Tompkins and Christopher Bird, which portrayed vegetal life as exquisitely sensitive, responsive and in some respects comparable to human existence, was generally regarded as pseudoscience. The authors were not scientists, and clearly the results reported in that book, many of them outlandish, could not be reproduced. But today, new, hard scientific data appears to be buttressing the book's fundamental idea that plants are more complex organisms than previously thought.

The research findings of the team at the Blaustein Institute form yet another building block in the growing fields of plant intelligence studies and neurobotany that, at the very least, ought to prompt us to rethink our relation to plants. Is it morally permissible to submit to total instrumentalization living beings that, though they do not have a central nervous system, are capable of basic learning and communication? Should their swift response to stress leave us coldly indifferent, while animal suffering provokes intense feelings of pity and compassion?

Evidently, empathy might not be the most appropriate ground for an ethics of vegetal life. But the novel indications concerning the responsiveness of plants, their interactions with the environment and with one another, are sufficient to undermine all simple, axiomatic solutions to eating in good conscience. When it comes to a plant, it turns out to be not only a what but also a who -- an agent in its milieu, with its own intrinsic value or version of the good. Inquiring into justifications for consuming vegetal beings thus reconceived, we reach one of the final frontiers of dietary ethics.

Recent findings in cellular and molecular botany mean that eating preferences, too, must practically differentiate between vegetal what-ness and who-ness, while striving to keep the latter intact. The work of such differentiation is incredibly difficult because the subjectivity of plants is not centered in a single organ or function but is dispersed throughout their bodies, from the roots to the leaves and shoots. Nevertheless, this dispersion of vitality holds out a promise of its own: the plasticity of plants and their wondrous capacity for regeneration, their growth by increments, quantitative additions or reiterations of already existing parts do little to change the form of living beings that are neither parts nor wholes because they are not hierarchically structured organisms. These ''renewable'' aspects of perennial plants may be accepted by humans as a gift of vegetal being and integrated into their diets.

But it would be harder to justify the cultivation of peas and other annual plants, the entire being of which humans devote to externally imposed ends. In other words, ethically inspired decisions cannot postulate the abstract conceptual unity of all plants; they must, rather, take into account the singularity of each species.

The emphasis on the unique qualities of each species means that ethical worries will not go away after normative philosophers and bioethicists have delineated their sets of definitive guidelines for human conduct. More specifically, concerns regarding the treatment of plants will come up again and again, every time we deal with a distinct species or communities of plants.

In Hans Christian Andersen's fairy tale ''The Princess and the Pea,'' the true identity of a princess is discovered after she spends a torturous night on top of 20 mattresses and 20 featherbeds, with a single pea lodged underneath this pile. The desire to eat ethically is, perhaps, akin to this royal sensitivity, as some would argue that it is a luxury of those who do have enough food to select, in a conscious manner, their dietary patterns. But there is a more charitable way to interpret the analogy.

Ethical concerns are never problems to be resolved once and for all; they make us uncomfortable and sometimes, when the sting of conscience is too strong, prevent us from sleeping. Being disconcerted by a single pea to the point of unrest is analogous to the ethical obsession, untranslatable into the language of moral axioms and principles of righteousness. Such ethics do not dictate how to treat the specimen of Pisumsativum, or any other plant, but they do urge us to respond, each time anew, to the question of how, in thinking and eating, to say ''yes'' to plants.

This is an article from The Stone, a series at nytimes.com/opinionator.